1. Field of the Invention
The present invention relates generally to automotive maintenance tools and more particularly to a device for allowing the remote adjustment of the vacuum modulator of an automatic transmission and the like.
This application is related to my co-pending U.S. patent application entitled "Modulator Adjustment Device", Ser. No. 07/335,714, filed Apr. 10, 1989.
2. Description the Prior Art
Automatic transmissions of the types used in modern automobiles have for many years used a manifold vacuum-controlled modulator to cause the transmission to shift from one speed to another. Early modulators utilized a spring-loaded diaphragm which, in response to engine manifold pressure, caused a shifting rod to move in and out of the transmission causing gear shifting to take place. The tension on the diaphragm and thus the amount of vacuum required to move the diaphragm enough to cause shifting could not be adjusted. It was later recognized that transmission operation could be improved if the spring force of the spring loading the modulator diaphragm could be selectively varied. In order to accomplish this change, an adjustment screw was provided. However, in most instances the screw was either placed in the vacuum passage, or itself provided the vacuum passage, and as a consequence, in order to adjust the screw it was necessary that the vacuum line be disconnected and a tool be inserted into the tube fitting to make the adjustments, with the vacuum line subsequently being reconnected. This involved a difficult and time-consuming process because the screw could not be seen inside the tube fitting and accurate adjustments could not easily be made. Furthermore, the adjustment could not be made under normal operating conditions.
As described in my above-identified co-pending Application, the disadvantages of the prior art have now been overcome by the provision of a means for enabling adjustment of the setting screw without requiring that the vacuum line be disconnected. This is accomplished by the provision of a fitting having a gear-toothed dial wheel which is mechanically coupled to the adjustment screw and which includes a coaxial vacuum passage so that adjustments can be made with the vacuum coupling intact.
However, before the present invention, in order to turn the dial wheel it was still necessary for the mechanic to physically locate himself in the vicinity of the modulator in order to make the required adjustment. This of course meant that, unless the car was engaged to a dynamometer, adjustments could not practically be made under operational conditions.